HIGH-LEVELS OF P-GLYCOPROTEIN DETECTED IN ISOLATED BRAIN CAPILLARIES
HIGH-LEVELS OF P-GLYCOPROTEIN DETECTED IN ISOLATED BRAIN CAPILLARIES
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DOI：
10.1016/0005-2736(93)90083-c
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发表时间：
1993-08-15
期刊：
影响因子：
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通讯作者：
BELIVEAU, R
中科院分区：
文献类型：
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作者：
JETTE, L;TETU, B;BELIVEAU, R
P-糖蛋白(P-gp)是一种高度保守的膜蛋白，表达于多种多药耐药细胞系中。用抗P-糖蛋白的单抗C219(MAbC219)，用免疫印迹法检测人、牛和大鼠脑毛细血管中的P-糖蛋白。单抗C219在从这三个物种分离的脑毛细血管中检测到一个180 kDa的蛋白质。从人脑分离的毛细血管中检测到的抗原数量最多。通过竞争抑制单抗C219与合成表位VQEALD的结合来评估特异性结合。脑毛细血管蛋白的糖蛋白性质通过其对N-葡聚糖酶处理的敏感性得到证实，N-葡聚糖酶处理使其表观分子量减少了5到10 kDa。此外，使用抗体C219、JSB-1和C494进行了免疫组织化学研究。牛和大鼠的毛细血管仅与单抗C219反应。抗体C219和JSB-1均可见人脑毛细血管浓染，而抗体C494仅见弱染色。这些结果清楚地表明，P-糖蛋白在血脑屏障(BBB)部位有较强的表达，提示该蛋白可能在调节某些分子进入中枢神经系统或调节BBB的分泌功能中发挥生理作用。
P-glycoprotein (P-gp) is a highly-conserved membrane protein expressed in various multidrug-resistant cell lines. P-glycoprotein was detected in capillaries isolated from human, beef and rat brains with a Western immunoblotting procedure using the monoclonal antibody C219 (mAb C219) specific for P-gp. The mAb C219 detected a 180 kDa protein in brain capillaries isolated from all three species. The largest amount of antigen was detected in capillaries isolated from human brain. Specific binding was assessed by competitive inhibition of mAb C219 binding by the synthetic epitope VQEALD. The glycoprotein nature of the brain capillary proteins was confirmed by its sensitivity to N-glycanase treatment, which reduced their apparent molecular mass by 5 to 10 kDa. In addition, immunohistochemical studies using the antibodies C219, JSB-1 and C494 were performed. Bovine and rat capillaries showed reactivity only with the mAb C219. Heavy staining of human brain capillaries was observed with both antibodies C219 and JSB-1, while only weak staining was observed with antibody C494. These results clearly show that P-glycoprotein is strongly expressed at the blood-brain barrier (BBB) site and suggest that this protein may play a physiological role in regulating the access of certain molecules to the central nervous system, or in the secretory functions of the BBB.